The incorrect tax rate on the invoice#
If the tax rate on the invoice is not valid, please review your WooCommerce tax rates. Also, please edit this particular invoice and check the chosen tax rate:
Incorrect rounding on the invoice#
Make sure that you have the Number of decimals option is set to 2 in your WooCommerce settings:
Read more on setting taxes in the How to Configure WooCommerce Taxes Complete Tutorial.